Hydraulic marine steering gear for operating the rudders of ships



Nov. 30, 1948. w. T. PRlTCHARD 2,455,090

HYDRAULIC MARINE STEERING GEAR FOR OPERATING THE RUDDERS OF SHIPS FiledJune 8, 1944 3 Sheets-Sheet l NlfENTOR. I {(WWJJJJZJZM 197' 7' ORNEYFiled June 8, 1944 Nov. 30, 1948. 1 w. 'r. PRITCHARD 2,455,090

HYDRAULIC MARINE STEERING GEAR FOR OPERATING THE RUDDERS 0F SHIPS 3 Shee'ts-Sheet 2 INVENTOR.

A 7' TORNEYS 5 Sheets-Sheet 3 I A 7 TOfPNE Y5 W. T. PRITCHARD HYDRAULICMARINE STEERING GEAR FOR Nov. 30, 1948.

I OPERATING THE RUDDERS 0F SHIPS Filed June 8, 1944 Patented Nov. 30,1948 HYDRAULIG MARINE spun-nine ornnn non oenna'rmamnn ltUnnnnsoFwsnl-rs Wilmot T.""Britcha rd, Seattle? waish assignor to "stetsonRoss Machine flbihpanyfi Seattle, Washg a corporation or Washington 1"Application J unei 8, 1944, 'Serial N6l539,342 'U l aiimS. (Clfi'fifl 52) 1 invention relates to hydraulic marine "steering gear for operatingthe rudder of a ship.

More particularly my invention relates'to' "providing in ahydraulicmarine. steering"mec'lia- 'nism,.for.varying the speed of response ofaships rudder to the pilot wheel 'such varying being of a controlled,adjustable, and continuous character throughout apredetermin'ed range'ofcapaci- .ties of the pump as between 50%to-100 and suchvarying :beingrendered possible without-releasing the force operating at a givenmomentto maintain the rudder either in a given position oninmotion. Also, myinvention provides for varying of-the character above deso'ribedfthecapacity of not only-one pump but two pumps in combined operation whenthe rudder is in motion or without in any wise interfering.with'thesteermg.

In a ship having a hydraulic steering.gear (sometimes called an engine)for operating'the rudder, it will be understood the operation of thepilot wheel inthe pilot house actually .operetes to .pump oil in acylinder assembly called -the forward .telemotor,.which may belocated-close to the wheel orjust beneath the wheels 'Thistelemotor ishydraulically. connected to an after -teie motor. The. plungers of theafter telemotor are connected to .gear mechanismcalled .difierential,whichinturniunctions as control means forthe swash plate in a -variabledeliveryn type of pump thereby determining-the capacity of the variabledelivery type. of ..pump. 1 From the foregoing, it willbe understoodthatldue to hydraulic connection from the forward. to the.- afterftelemotor, any movement of the steering wheel will produce aproportional movementof. the pump control. and therefore. movement ofithe rudder. At the same t-ime connected means is setv i1rm0- tion tostop the rudder at-the-position determined by-the wheel and to restorethe swash plate to neutral position.

Such hydraulic steering gearfor ioperating the rudderv has thetillermounted upon-the rudder stock and has each end of. the tiller connectedto the center of a ram-disposed to move in and out of cylinders, onecylinder for each end of the ram. Thus, as there are two rams'ftherewould be four cylinders. To pump the oil i'nto'the four cylinders toactuate theiram, ordinarily there are two pumps, often referred toas'the two-pump units.

Due to the necessity at times of maneuvering the ship'whileadheringclosely to ag'iven course and to the necessity ofoperating'under routine conditions, and due to the necessity ofproviding for wear of parts; lost motion," leakage ofhy- 'draulic fluid,and due to the necessity at'the'same time forproviding for emergencysituations as naval. engagements, storms,failure for mechanical reasons,maneuveringfiin. tortuous""'narrow 2:2 'channels';ortrarisfer of' oilorany -transfe1fat"sea to'anoth'er ship"tvhe're-operation in unisonisrequired, there"develops a wide-range'of requirements" "respects"varying" speeds of response of the rudder to the pilot Whee1.""EXpre'ssed-inother words, this"means"varying the amount'oi "powertb'beiaifrplied to'the'rudder or'varying the capacity of the hydraulicpumps; A primary 1 object 'oriny invention is to" providefors'uchrange-of requirements ano-parucuiar1ytnat suchvar'ying snan' beof a controlled, adius-table,and" continuous char-- 'a'cter throughout a"predetermined range; asbetweeii'so %""-to100inclusivefof capacitiesof awearable eapacity type' pum "'Thepbjecfibf' my invention is to priividemechanism hi'chshall render-possible such varyingfof *th apa'city' ofthiilimp' orpum 's IE'Ven Whfle'the l'iid dr is him!- ing.-'- "-Be wpartiou'larlywioted that the-successful carrying" out" "of operations?'at sea and in" the emergency situationsaboveset forth; niaydependwholly orindarge part'upon the steering-mechanism be'ing capable ofchaini'ginQ'thSpeed of rudoer movement at all times." "In snorti rpropose "providing a"steerihgrnechariism 'lriaving a rudder connectedto" a pim ality"of rams and' cylinders hydraulically operatedf'by a=pluralityb'f'variable outpuvpum'ps"ivl'iicwmeclianism ischaracterizedby""kiihg""oapeible 0f (5156fatl'il finder a" selectable predeterminedmaximum output of"thepunips singly or jai in ei daeme-smetime'havi'ngs'uch "Output capaplepr change even "while the riidderismoving.Thus"when{thefshipis bein'g'k'teer'ed ina zigzagcoursoimdodeinitorpedoes-not asecond of time would beilfostin"'caus'ingres'ponseiof'theship to" thddesiredhapacity ofthe pum s inapplyingthedesired-power'to th trudder. I'p'urpose providingfor suchvarying'pf capacityof a continuous character not only of .one pumpoperating "butalso orthe'twupumps of a dual installationroperatingiiricombination.

"Since"the"'utijlity of a 'ship' depends' inlarge measurei-uponitsmaneuverability and this in turn depends upon ithe' properend efficient.operation or the rudder'withrespect'tothe speedo'f the "Ship,a"primary"objectof"my'irivention is a) to proivici fofadjustihg'thecapacity "of'the pump to minimum requirements, ""(b) to "provide"for? in'- creasing the "power applied: tothe rudder by inereasingfthec'a'pacity of th'e pump in emergency when"h'igh' activityofthe rudder is 'necessar and (trio-pr vi e seouri'tyobtainedby havinga' 'wide range "of selectivity ofoi era'tion of'parts of a diial unitmechanism.

illustrating a situation-where' myinvention solves a particularly'di'fficult probleni'of maneuvering requiringg' iri ari'e'i'rceptionallyhigh degree, exactnessoFsteering,"let it"b" noted'in "thetra'nS- fer ofoil at-sea to another' ship; known. as'ioilmg; the""oiling"ship"whichint/111 be assumed is "eqlli p'fid' with rhyfinvrition an'dithe shipiciwmaintain the distance.

3 ing the oil arerequired to run parallel while the oil is being pumpedfrom the oiler to the other vessel with a plurality of heavy linesextending from one ship to the other. The ships are secured in spacedrelation by heavy hausers but they must be close enough to permit thebooms to swing the oil lines to the ship to be supplied with oi. Theships are then steering slightly apart to Under such circumstances, themoving of the rudder at an exceedingly fast rate when in a rough sea andthe ships are moving, there is required a particularly active rudder forsuccessful carrying out of the transfer. The ship being supplied withthe oil may have a very slow steering mechanism and therefore thesteering mechanism of the oiler must provide the safety for bothvessels. It will be understood that the vessels are proceeding at areatively slow rate and this also is a feature which increases therequirement for an active rudder on thepartof the oiler. Myinvention hasbeen found successfully to solve this situation.

Also, a primary object of my invention is to provide in effect anadjustable cam which is subject to being moved bythe pilot wheel.

Another primary. object of my invention is to provide means for varyingthe discharge volume of a cam controlled pump to obtain greater or lessspeetl of response of the rudder to the pilot wheel and at the same timenot interrupt the operation of the pump or the force applied to therudder which may be operating to hold it in a given position to which ithas been or is being moved.

The above mentioned general objects of my invention together with othersinherent in the same, are attained by'the mechanism illustrated in thefollowing drawings, the same being a preferred exemplary form ofembodiment of my invention, throughout which drawings like referencenumerals indicate like parts: I

Figure 1 is a somewhat diagrammatic view showing an hydraulic steeringgear embodying my invention; I

Fig. 2 is a side elevation of the same;

Fig. 3 is a vertical sectional view with parts in elevation and partsbroken away, taken through the pump stroke adjusting means, differentialcontrol, and pumpj' Fig. 4 is a view in longitudinal section with partsin plan through the pump stroke adjusting means taken substantially onbroken line 44 of Fig. 3;

and

Fig. 5 is a diagrammatic view showing pipes, valves and differentialcontrol means.

The most important units of mechanism that g0 to make up thissteeringgear are designated in a general way in the drawings by thefollowing numerals: I0 is a hydraulic ram means connected with a shipsrudder; H is a steering control means or forward telemotorsuch controlmeans is usually manual'y operated as by a pilot wheel in the pilothouse but may be operated automatically by a Sperry unit; l2is ahydraulically operated after telemotor; i3 is a constantly drivenvariable volume pump, two of which are used to provide alternate orcombined operating means; It is a differential gear and cam unit formingpart of the pump controlling means which means is connected to and iscommon to each pump; i5 is a pump volume adjusting unit herein referredto as a stroke adjusting device, one being provided for each pump.

Preferably a pump unit 13, a differential gear and cam unit l4 and astroke adjustment unit l5 are assembled into one piece of mechanism asshown in Fig. 3, and two of these assemblies are used in each steeringgear as shown in Figs. 1 and 5.

The hydraulic ram unit l0 comprises two reciprocable paralel plungers orram members 16 and l! having their end portions disposed respectively infour hydraulic cylinders l8, I9, 20 and 2i. A tiller 22 extendscrosswise of the ram members I3 and I! and is operatively pivotallyconnected therewith for angular movement thereby. An upright rudder postor stock 23 is keyed to the tiller 22 intermediate the length of saidtiller. A rudder 9, shown fragmentarily in Figs. 1 and 5, is secured tothe stock 23. When either of the two ram members H3 or H islongitudinally movetl the tiller 22 and the rudder 9 connected therewithwill be anguarly moved to steer the ship. Power may be applied to eitheror both ram members l6 and I1 and when one ram member is moved in onedirection the other ram member will necessarily be moved in the oppositedirection. Fluid under pressure is supplied to the cylinders l8, I9, 20and 2i through suitable pipes hereinafter described. To provide two-wayrudder actuating means, the cylinders l8, I9, 20 and 2f are operated inpairs and opposed relation.

Anguar movement of the tiller 22 also transmits a follow up motion totwo horizontal gear racks 24 in order to stop the movement of the rudder9 at the position predetermined by the movement of a pilot wheel 30.Said gear racks are moved by means such as rods 25, upright levers 26,shafts 2i, upright levers 28, and links 29. The rods 25 are pivotallyconnected with the end portions of the tiller 22 and the links 29 arepivotally connected with the gear racks 24.

The gear racks 24 transmit follow up movement to the differential gearand cam unit l4 through which the pump is controlled as hereinafterdescribed. In order to provide for simultaneous movement of the racks 24in the same direction, gear segments 8 shown diagrammatically in Fig. 2,are provided in the means connecting one of said racks 24 with thetiller 22.

The steering control unit or forward telemotor H is of standardconstruction, is usually located in the pilot house of the ship and isprovided with the usual manually operated pilot Wheel 30. This steeringcontrol unit H has a hydraulic connection through pipes 35 with theafter telemotor l2.

The after telemotor l2 may comprise two hydralic cylinders 32 and 33operatively receiving the end portions of a ram or plunger 34. Theplunger 34 has an operating connection with two upright gear racks 35 bymeans, such as a forked member 36, lever arm 31, shaft 38, lever arms39, and links All. The gear racks 35 transmit movement to thedifferential gear and cam unit 14 through which the pump is controlledas hereinafter described.

Each pump unit i3 is of a rotary, variable delivery or displacement typewith axially disposed reciprocable pistons operated by swash platemeans. In the drawings 4 l Fig. 3, is a pump housing and 42 is a frontvalve or manifold plate connected with inlet and discharge conduitsmeans 43. 44 is a cylinder block having cylinders 45 for the receptionof pistons 46. A suitable number of pistons 48 and cylinders 45 may beprovided and said pistons and cylinders are arranged at spaced intervalsaround the axis of the pump and substantially parallel with said axis.41 is a motor driven main shaft that is connected by key means 48 withthe cylinder barrel or block and by universaltype-jointmean's i withswashplate means 50. 5 I--is-*'an angularly aiddustable receptacle ortilting-box within which-the swash plate means 59 is'- rotativelysupitiorted by -bearing means -52. 53 are connecting rods that connectthe pistons it' with the swash plate means 50. Each pump shaft 4'! isconnected with an electric motor t i, "Fig: l and 2; by which* the pump-is driven cons-t'ahtly when in 'use.

When the tilting box "5 I; and swash'platemeans 56' are po'sitioned at'right angles to the lshaft il, as shown 'in' Fig-.- 3; rotary motion fthe swash plate'itill and the cylindrical bar-rel t willnot 1 produceany longitudinal'moilement of the-pistons 5 I3 and -no-- liquidivill bepumped. l -"Ii the tilting bo'x it and swash pl'atemeans 5t areinclinedrela- 'tive to the axis offshaft i it then I rotary movement of these'parts and: the barrel- M will reciprocate the pistons 46. The amount ofinclination im- -parted to the tilting box -54 and swash platemeans -5llwill determine the: stroke of: the .pistons 56. -Ihedireetion ofinclination of these-parts Hand E 50: will determine which ofthe-conduits 63 is an 'inletandw-which is anoutlet conduit. Thus thed-irection of flowof the liquid that is being. circulated by a pump'unit lt :may be varied, neuiitrali-zed;:orwreversed' by. angularadjustment of the tilting box 5! :andswashplate means fit. The @above;mode of operation of the pump is that iwhich charactei'lzes thistype ofvariable delivery --.pump.

nLet-it betnoted'that' instead of theraxially disposed piston type ofvariable delivery pump above i described,..the radiallyledisposed pistontype of t ivariable delivery pump maybe substituted or em- .wployed.

@The means for tilting the box 5i. comprises. aarearwardly.rextendingstub shaft 55 rigidly coni nected with said boxElto'one sideof the center othereof (it e.,- shaft-55 lies behind mainshaft ll in Thearod' 5i extends upwardly out of the pump .ehousingthrough'bearing and packing means 58. The upper end" portionof saiclrod5'17 is positioned 'within thesh'ousing 59 of thetpump stroke ad-:Jjustmentunit; i5; Figs. 3 and 4, anclis provided :witha forkedportionfiil that is connected by links ii I" with-one-end portion of a leverarmfi2.

- The :lever arm 62 is'fulcrumed on adjustable :pivot-meanscomprising ablockdit movable in a ;=.slot:fi iin;said lever arm'62. The-blockt3 isful- .-=cru:medwon:an adjustable pivot pin 65 that is car.riedby'two-spaced apart parallel pivot carrying bars 6t..-*The-respective end portions of, the pivot acarrying bars-66 aresecured to two head slides 61 and--58 that are supported for movement intub- :nlarextensions 69 at the two'encls of the housing 59. A coverplate "Hlis secured to the tubular extension-69 that houses theheadsl-ide ti and said ahead slide 6? is preferably provided with anadjustable stop bolt ll adapted to engage with the cover plate H! tolimit adjustment in one direction cured as by cap screws 35 to the headslidej68.s

Theadjust-ing screw His-threaded through anut =.member-! 'i that isrotatively held in a hub 511' in l. the icover-plate 1'12. -An adjustingwheel 18 is 'sevoured torthe nut member :l6rbycapscrew-79.; A

i6 186M:is -iearried bysi thes;adiustingvwheelui t -and nto'azre'cess'itl in the cover plate adapted o-loole lz' topreventany butdesired :movement of the wheel 'lB. An aid justable' stop .screw- 82 ispro- 5 vid'e'd' in the ad'j usting wheel 1 Biol iimiting movemeto'theright'f-Figl fii, on'thezadjusting. screw 73. "'lurningltheiadjlisting wheel lfi'w-illturn thenut mb'eri lfiiiandiiadjustthe position of the pivot p t longitudinailyr as'.:respects. the lever t2. *The end portionsofi'theilevenl'fih'shown atthe rightin-Eigs; Sa'hdApis pivotally connected with 1 a forked rodifi'e iIheurodl83extends downwardly and-iis ifixedly' se'cured to a :plateor'crossheadM that is verticallyrzmovable: in the shousing- 85 of thedifferential 'g'earaand scam unit M. *Means such. as :guidei'members 86'slid'ablysupport the edgeipo'rtions of thezplate'sor crosshead 84. Thellplate M'carries'two roam: rollers B'l'thattare positioned'inengagenienti with aicam 88'fixedly setcuredhtor.punposesuof'toperation.on a sleeve 89. Rotary: movementi of the zcam 88 will .LsIidably movethe plate or crossheadfflfliand this will move the: forked rod" 83oandiangularly move the. lever arm- 62 about *thes adjustable fulcrum pivot55. 25 Angular movement of.:the lever 62 will vertically move'sthepump'adjustingz'rod 5'! and change the angular position? of thertiltingbox =5 I andaswash plate '59 inithe pumpuunit l3 thus adjusting or c'varyin g---the a-pistOn istroke: of. the pump. Mani- 3i) festly,shifting of.the ulcrum -pivot 65*varies the 'lengtha ofithe levertarmsoneachiiside of said pivotwhereby: the amountofs'throw of pumpadiujusting rod: El isiwaried.I-llObviously suchshiftaingonzadjustingzofthafulcrum pivot 65 may be 1:5, done" while:the?mechanismsv is i in :operation and force is b'eingzaipplied to' therudder 9.

A shaftitll} Figs; 3iand 5, is disposed within the isle'eVei'fSB; that"carries .the cam 88. Each shaft 9i! has aifixedlyrseouredigear wheelQL'Fig. uaithereon' that is .enga-ged by'one of theupright racks'iefiwhereby each shaftfln'may be'rotatively moved-finresponse" 1102movement? of the after telemotor l2 through' forked link 36and-1connecta ingim-eans. :4 Each *shaft'ififliand 'the sleeve 89thereon "arez'conn'ected lWith each sother by differ- "entialgear-means; comprising a 'bevel' gear 92 that is fixedly secured to theshaft Miami meshes with t other: bevel ge'ars 93 l whichvare carriediibyand 1 fixed wto' r-ithe l' sleevemifil .The bevel gears l 83' also mesh:with another bevel gear ied thatis rotatively mounted on the :sleeve89.1 Thei'bevel-gear 94 is secured to ajsgear wheelififi thatmeshes-with 'another: gear wheel 96 ion a: counteresh'aft 9 l The"ir'count'ereshaft:3iIv has ar'geanwheel'cfifl that isenogagedi.byiionelz ofathex horizontal geart racks 2t --i v'hich zisazconnectediwithwthe hydraulic ram .o'unitfiii.

I' :cDue to :said idifierentiali mechanism and tiller connectionsthZGOHghZiIGdSL ZEfiUhGECW11 823 will al- 0- waysbesresitored toitszneutral position shown in Fig. 3 after movement oflilthezp'ilotwheel" 30 "has ibeenubrought to irestfat any desired: position.-1When .the'liafteriftelemotor 1- z' 'moves the upright :rackszz'iE in.:response;to force communicated. from the pilotwheelim eachishaft 90willbe'rotatively imovedithe'rebygi This 1 will transmit rotary 'motion'in one iolirectionto' theicam58 8 through: sleeve W89randtbeivelrgearsti'QZuandbQ3; t.This1imotion of the cam 88 will becommunicateditwthe pump 'vox unitsils".thrOughcipartSS'B1e84;:S'83',-i62; 5 Liand 5'5 ivandi 'willi'iangularlysL-mOveittheswashplates 50 v ithereofsintoizdesited zoil de'liveryr position. Eithervoneson rboth'iof lthe'ipumps -cwill abe'afieoted; :deapending:onewhetherazone tor bothi #pumps are inisreadilyaretractableispringrpressed lockingtplungerii iazuse.iiilslsuallytin. inor'maliioperatiomiof thefuship only one pump will bein use. The delivery of oil or hydraulic fluid under pressure to the ramI operates said ram. Movement of said ram, communicated through tiller22, rods 25, and associated connecting means, will move gear racks 24.Gear racks 24 will actuate gear wheels 98, counter-shaft 9'I,gear wheels95 and 95, bevel gears 94 and 93, and sleeve 89 back to the cam 88. Thusmovement of the ram means I0 automatically functions to return the cam88 to its original neutral position. ;When the ram has traveled apredetermined distance proportional to the distance the pilot wheel 30has been moved, the cam will be brought back to the neutral orinoperative position. Usually an indicator (not shown) is provided inconnection with the pilot wheel 30 and the hereinabove describedmechanism operates so that the .ships rudder 9 will always beangularly'moved the number of degrees indicated on this indicator in thedirection indicated by said indicator, and thus the rudder position isdetermined.

Two pumping assemblies capable of separate and independent operation aswell as combined operation are used in connection with each ram. Each ofthese assemblies comprises a pump I3, a difierential gear and cam unitI4 and a stroke adjustment unit I5. A control valve 99 of standardconstruction is connected with each pump unit I3 by the two conduits 43.

The control valve 99 that is connected with the uppermost pump unit I3shown in Fig. 5 is connected by main supply pipes I00 and I'0I with theouter end portions of the respective ram cylinders I3 and I9. Similarly,the control valve 99 that is connected with the lowermost pump unit I3,shown in Fig. 5, is connected by main supply pipes I02 and I03 with theouter end portions of the respective ram cylinders and 2 I.

Valves I04, I05, I06 and I0! are provided in the respective pipes I00,IOI, I02 and I03 preferably near the locations where these pipes connectwith their respective cylinders.

A cross pipe III provided with a valve I08 is connected between thepipes I00 and I03 and a similar cross pipe I09 with: valve H0 isprovided between pipes IM and I021.

Four by-pass pipes II2,.Ii3, H4 and 5 are also connected with the outerend portions of the hydraulic cylinders [8, I9, 20 and M and arerespectively provided with valves H6, H1, H8 and I I9 preferablypositioned near the cylinders.

The by-pass pipes H2, H3, '4, and H5 are interconnected as shown in thelower portion of Fig. 5 and provided with valves I20, I2I, I22, and

I23 by which by-passing of liquid between different cylinders may beselectively controlled. Any suitable arrangement of liquid supply tanksand reservoirs may be connected with the bypass pipes H2, H3, H4 and "5by pipes I24 having valves I25 therein.

The conduits I00, IOI, I02, I03, I09 and III, Fig. 5, are high'pressureconduits. All of the remaining conduits shown in Fig. 5 are low pressureconduits. the low pressure conduits are therein shown by dot and dashlines to distinguish them, in this figure, from the high pressureconduits which are shown by full lines.

In the operation of this ships steering gear, movement of the wheel ofsteering control unit M will produce movement of the ram member 34 ofthe after telemotor I2. This movement of ram member 34 will betransmitted through parts 36, 31, 38,.39, 40,35, 9|, 90, 93, and 89 toAs Fig. 5 is a diagrammatic view the cam 88. Rotary movement of cam 88,Fig. 3, will act through rollers 81 to vertically move the crosshead 84.This will vertically move the forked member 83 and angularly move leverarm 62. The angular movement of lever arm 62 will vertically move pumpadjusting rod 51 and thus adjust the position of the swash plate 50. Thepump I3 is driven continuously while in use and the position of theswash plate 50 determines the stroke of the pump pistons 56 ashereinbefore fully explained. The cam 88 is designed to provide forrelatively rapid movement of the crosshead 84 between the position shownin Fig. 3, in which the pump unit I3 is neutral and the piston stroke iszero, and a position of full or maximum pump stroke in which one camroller 81 will ride the larger diameter of the cam 88. Cam 88 and strokeadjusting means I5 move swash plate 50 or tilting box 5|.

The mode of operation of my invention is set forth in part in giving thetechnical description above. The following will supplement the above.

Recognized specification covering steering gears provide that such mustbe designed to move the rudder from hard over to hard over through 70within 30 seconds when the ship is traveling at full speed ahead at themaximum designed ship horse power without the hydraulic pressure of thesteering mechanism exceeding the rated pounds per square inch when asingle pump is operating at not over 90 of full stroke and withoutexceeding the rated horse power of the pump motor specified.

The mode of operation of my invention is characterized by providing aninfinite number of pump volume or capacity adjustments as between 60%and inclusive, thus rendering the varying of the pump capacitycontinuous in character within said range. The magnitude of the throw ofthe cam 88 is designed to move the swash plate 50 of the pump fromneutral position or zero capacity of delivery to the desired specifiedmaximum, 90%, capacity of the pump to which it is connected when theperformance of said pump is as above specified. By providing theshiftable fulcrum pump stroke adjusting mechanism I5, Fig. 3, myinvention provides for the swash plate 50 or tilting box 5| to be causedto move and respond to the movement of the cam 88 through an infinitenumber of adjustments, that is, through a continuously varying capacityof each pump with its cam acting singly in the range of 60% to 100%inclusive or the combined capacities of said pumps and their cams whensaid pumps are operated in combination. For example, when it is desiredto have the power of both pumps available to insure desired rudderactivity, both pumps may be put under load by employing the desiredcombined capacities of said pumps ranging from their combined minimumoutput to their combined maximum output. My invention provides thiscontinuous varying adjustment of capacity of each pump or the combinedpumps while at the same time without releasing the force which at themoment may be operating to maintain the rudder in a given position or inmotion. This adjustment is accomplished in my invention by shifting thefulcrum 65 through the screw I3 and associated mechanism connected tohand wheel I8.

This adjustment provides the infinite number of adjustments because itmay continuously vary the fulcrum 65 of the pivotally mounted pumpadjusting means by reason of its slidably mounted fulcrum B5-saidfulcrum 65 being thus mounted to trollablecontinuously increasing ;and.-.decreasing I means i as-respects pump capacity.

In the. eventthat the magnitude of the throw ofithe camlfitdesignedto-move the. swash plate fill'of-the fromuneu-tral .-or ,zero:capacity of dGHVBI'zSf'ftO ICSS or more; than..-the 490% strokecapacity, then-obviously my -invention may-{be employed to increase ordecrease L respectively: the effective throw of the cam 88 by suitablesli-fting toadjust-ithe capacity aboverthat atwhich -ithas been=.;working;As. an: :eXample;.--while a the pump initially-maybe designed-to-give arequired degree. ofeservice at90%' of its capacity, when parts bewcomei-wornor-smallxleakages developit maybe i neoessary-toladjust thepumpzabove said 90%; e

Itwill "be understood that the-cylinders-.-l 8, :J 9, Eflfiand 2 H with:theirconneetingpipes, both :high

pressureandr bypassing: pipes, are filledwith: hy-

pressure to cylindersl 9*3Ild720 as'one-pain -cylinders 1.8 sanduz l asranother pains-the: oil under pressure; therein will-exertpressureon-both rams lfitand H. use and twovcylinders; as 20 and ZLware bypassed10 to exhaust oredischarge fluid, at the, same time... Thusopposed'cylinders wouldbe cylinders I 8 and. IE, or '29 amaze or 88 and20,01. lQT'andZ'IL.

The rams...l6 and l! always move in-opposite directions due to theirinterconnection by thetiller 22 and irrespective of whether force is.-.applied to one or both of said rams. Also, whenever these ramsare'moving, two cylinders will. always be exhausting or by-passingifiuideither back to a pump or from one cylinder to another.

When'any twocylinders are idling,i. e.,' are notcommunicatively.,connected' with a pump. that isin operation, then it becomes necessary.to in.-- terconnect said .cylinders through the by-pass conduits H2,-ll3, 1M andrl l5. One way to use both pumps to supply-fluid underpressure to both rams isto open valves I04; Idfiflflfi and I01: 1 andclose all. other valves. When this is done. the-two pump units will beindependent1y1con-- nected one with the two cylinders l8 and {Sandtheother with the twozcylinders Hand ZL- If valves I08 and-l It. are openedalongwith valves I04, I05, I06 and, I8} then the. circulation sys--terns formed by conduits we, NH, Hi2 and 1% will .be 'communicatively.connected with each other and the two pump units; can be: used jointlyto. supply fluid'under pressure in both rams. If the use of one of theadjustablepumpunitsis discon-.:- tinued while valves ,lM,-lilfi;r;'lilti, illl; H33 and.-

30111"! are openand all by-pass valves are closed by the oi1,th'en%the:oiluunder pressure irt cylinder? 1 Bord 9 willzbe exertedoniram-ifib. Similar opera-- tion;.-'o'ccurs as-to ram l lrwhen oylinders20:0r2L... are" subjected t c-"oil: under pressure and cylinders i ii and 1-9arez-bypassed y Eachpumphasra capa city to #operate? [both qrams' l 6*and 1H. By protainedon the .rudder g to"hold it-in':whatever post tioniit may be theneoccupying. through-the stroke v adjusting unit 5 5interposed between camrfltrand the swash plate 5Eljrit is obviousthatagreat'range of: selectivityoi the number of cylindersas 'Well as H theeapacityhunder which said. cylinders are to ,be operated is providedbyi'my 'i'nvention: without in any wise interferin'gnwiththernormaleopera-tion' of the pilot wheel or otheniparts of-rthe'steeringmechanism.

The stroke adiusting unit l5 operates between? the cam 83 and'the1tilting;boi 5! or swash plate 50 to vary the eifective stroke ofthe cam, i. e., to vary the amount of angular movement that apredetermined constant throw of the cam 88 will impartto the' swashplateau- As such adjustment is made by moving the pivot or fulcrum oflever 62 toward and away fromthepivotmember that connects the forked arm63 with the lever 52 the pump adjusting rod 51 and tilting box 5l -fandswash plate fiflwi'll'always bereturned to thesameneutralposition"irrespective of how much" they ders. When fluidund'erpressureisbeing supplied to one ramcylinderthen' fluid." is always exhaust- Theterm" inc." from; an opposed ram" cylinder. opposed cylinders refers toany two ram cylinders in which ram members are moving in opposedrelation, i. e., one to admit fluid and the other then theother'adjustable pump unit alone; can be used to supply'fluidunder-pressureto both rams. Thus, when a pumpunia-with itsassociatedpiping isg operating;.-it. will always-take. care of the exhaustfluid'from the cylinders opeposed to thoseto which it is "supplying fiuidnunswder pressure.

Also, both adjustable pump units or either'adjustable pump unitmay beuse to supply fluid 1.40! under pressure to only one cylinder at atitre.-- vidin'grior' a continuing..varying'reapaci-ty of-=the pumpsand'ithis while the"; force: is 'fbell'lfgomainr-i member l6.- Similarlif high pressure valves.

I06, l01,-l08 and Ill] and low pressure valves 1 it, H7 and I20 arevopened and all other valves closed then both adjustablepump units maybemused-jointly, to apply. power. through ram member .l Tvvh ile rammember lfiidles or either.

of. saidadjustable pump units maybe so-used if the .otherpump unit isnot operatingn I It-is also possibleto use the two .opposed .cyl. indersIB- and Zl as operating cylindersin con-. nection' with bothioreither:of the adjustable. pump units by opening high pressure valves 1 i! 5,;IOII;-l fl8;and .l l0 and low pressure valves l lB,-,I l8 and. 123 andclosing all. other valves. In a similarqmanner it is .-possib1eto usethe two opposed cylinders :18 and 28 as operating cylinders inconneotionwith both or either of the adjustable pump: units-by openinghighpres-v sure valves 104 106; 38 and Hi] and lowapresev sure valves 1IT, 1 I B and l 2i and'closing: all other." valves.-

Obviously .5 when the uppermost I adjustable. pumpiunit. lshowni-n' Fig.5 -is beingused to: apply: power only to the ram member i 6 then thevalves I08 and I I0 may be closed. Similarly these valves I08 and H0 maybe closed when power is being applied to the ram member I1 only by thelowermost adjustable pump unit shown in Fig. 5.

From the foregoing description it will be seen that the two adjustablepump units can be used jointl in connection with all of theram cylindersor in connection with any two opposed ram cylinders or either of saidpump units can be used singly in connection with all of the ramcylinders or in connection with any two opposed ram cylinders. Thus, inthe event parts of the steering gear are damaged or become inoperativeit will always be possible to operate the steering gear successfully aslong as one pump unit and two opposed cylinders and the connectionstherebetween remain in condition for operation.

The use of the various above combinations of cylinders is possible withmy invention without even momentarily interrupting the steeringoperation or normal operation of the rudder due to the fact that changein pump capacities may be made without interrupting the force beingapplied to the rudder and thereby no loss of control of the maneuveringof the ship at any time results.

In the use of the two pump units independently, i. e., with both pumpsoperating and the two valves I08 and 109 closed, the pump'adjusting unitl provide a means for quickly and accurately adjusting either or both ofsaid pumps while the steering gear is in operation so that each pumpwill do its share of the work and neither pump will be a drag on' theother.

Obviously, changes may be made in the forms, dimensions, and arrangementof the parts of my invention, without departing from the principlethereof, the above setting forth only a preferred form of embodiment.

I claim:

'1. In a hydraulically operated marine steering gear mechanism forselectively varying the rate of angular movement of a ships rudder inrev sponse toa ships pilot wheel, the combination of a motion transfercam-like-means movable in response to a ships pilot wheel; andadjustable control means for varying the effective throw of saidcam-llke-means comprising a lever, a slidably mounted fulcrum for saidlever, and means for controllably sliding said fulcrum relative to theend portions of said lever, whereby the length of the lever arms of saidlever may be varied; and adjustable power means for moving a shipsrudder controlled by said cam-like-means.

2. A hydraulically operated marine steerin gear mechanism forselectively varying the rate of angular movement of a ships rudder inresponse to a ships pilot wheel comprising, a motion transfercam-like-means movable in response to a ships pilot wheel; rollers toengage said camlike-means; slidable cross head mounting means for saidrollers; hydraulic operating means connectable to a ships rudder; avariable output pump for hydraulically operating said hydraulicoperating means; a lever having one end portion connected to said crosshead and the other end portion connected to said pump; a slidablymounted fulcrum for said lever; and controllable means for sliding saidfulcrum toward and away from the respective ends of said lever to adjustthe effective throw of said cam-like-means.

3. A hydraulically operated marine steering gear mechanism forselectively varying the rate of angular movement of a ship's rudder inresponse to a ships pilot wheel comprising, a motion transfercam-like-means movable in response to a ships pilot wheel; hydraulicallyoperated ram means connectable to a ships rudder; a variable output pumpfor hydraulically operating said hydraulic ram means; a, lever havingone end portion operatively connected to said camlike-means and theother end portion to said pump; a slidably mounted fulcrum for saidlever; and controllable means for sliding said fulcrum toward and awayfrom the respective ends of said lever to adjust the effective throw ofsaid cam-like-means.

4. A hydraulically operated marine steering gear mechanism forselectively varying the rate of angular movement of a ships rudder inresponse to a ships pilot wheel comprising a motion transfercam-like-means movable in response to a ships pilot wheel; hydraulicallyoperated ram means connectable to a ships rudder; a variable output pumpdelivering liquid under pressure to said ram means; a cam-like-meansoperable by a ships pilot wheel; follow-up means connecting said rammeans with said cam-likemeans; a lever having one end portionoperatively connected with said cam-like-means and the other end portionwith said pump; a slidably mounted fulcrum for said lever; andcontrollable means for sliding said fulcrum toward and away from therespective ends of said lever to adjust the effective throw of saidcam-like-means.

5. A hydraulically operated marine steering gear mechanism forselectively varying the rate of angular movement of a ships rudder inresponse to a ships pilot wheel comprising, a motion transfeream-like-means movable in response to a ships pilot wheel; two rammembers connectable with a ship's rudder; cylinders in which the rammembers respectively operate; two variable output pumps; conduit andvalve means operatively connecting said pumps to said cylinders; twocam-like-means operable by a ships pilot wheel; two differential meanseach connected with one of said cam-like-means and connectable with aships rudder; two levers, each having one end portion operativelyconnected with one of said cam-like-means and the other end portion withone of said pumps; a slidably mounted fulcrum for each of said levers;and controllable means for sliding each of said fulcrums toward and awayfrom the respective ends of said lever to adjust the eifective throw ofsaid camlikemeans.

WIIMOT T. PRITCHARD.

REFERENCES CITED The following references are of record in the file ofthis patent:

